U.S. patent number 8,710,859 [Application Number 13/242,400] was granted by the patent office on 2014-04-29 for method for testing multi-chip stacked packages.
This patent grant is currently assigned to Powertech Technology Inc.. The grantee listed for this patent is Kai-Jun Chang. Invention is credited to Kai-Jun Chang.
United States Patent |
8,710,859 |
Chang |
April 29, 2014 |
Method for testing multi-chip stacked packages
Abstract
Disclosed is a method for testing multi-chip stacked packages.
Initially, one or more substrate-less chip cubes are provided, each
consisting of a plurality of chips such as chips stacked together
having vertically connected with TSV's where there is a stacked gap
between two adjacent chips. Next, the substrate-less chip cubes are
adhered onto an adhesive tape where the adhesive tape is attached
inside an opening of a tape carrier. Then, a filling encapsulant is
formed on the adhesive tape to completely fill the chip stacked
gaps. Next, the tape carrier is fixed on a wafer testing carrier in
a manner to allow the substrate-less chip cubes to be loaded into a
wafer tester without releasing from the adhesive tape. Accordingly,
the probers of the wafer tester can be utilized to probe testing
electrodes of the substrate-less chip cubes so that it is easy to
integrate this testing method in TSV fabrication processes.
Inventors: |
Chang; Kai-Jun (Hsinchu,
TW) |
Applicant: |
Name |
City |
State |
Country |
Type |
Chang; Kai-Jun |
Hsinchu |
N/A |
TW |
|
|
Assignee: |
Powertech Technology Inc.
(Hsinchu, TW)
|
Family
ID: |
47910609 |
Appl.
No.: |
13/242,400 |
Filed: |
September 23, 2011 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20130076384 A1 |
Mar 28, 2013 |
|
Current U.S.
Class: |
324/756.01;
324/757.05; 438/55; 438/17; 438/118; 257/777; 257/E21.525;
257/E21.521; 324/762.06; 324/757.04; 324/756.07; 438/15;
324/756.02; 257/E21.599; 324/762.02 |
Current CPC
Class: |
G01R
31/318513 (20130101) |
Current International
Class: |
G01R
31/28 (20060101); H01L 21/66 (20060101) |
Field of
Search: |
;324/756.01,756.02,757.01,757.04,757.05,762.01-762.06,754.01
;438/10,17,106-114,118,55,15 ;257/777,E21.521,E21.525,E25.013 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Phan; Huy
Assistant Examiner: Split; James
Attorney, Agent or Firm: Muncy, Geissler, Olds & Lowe,
P.C.
Claims
What is claimed is:
1. A method for testing a plurality of multi-chip stacked packages,
comprising: providing one or more substrate-less chip cubes each
consisting of a plurality of vertically stacked chips, wherein a
stacked gap is formed between two adjacent chips and a plurality of
testing electrodes are disposed on a top chip surface of each
substrate-less chip cube; attaching the substrate-less chip cubes
onto an adhesive tape with the testing electrodes away from the
adhesive tape, wherein the adhesive tape is attached inside an
opening of a tape carrier, wherein the tape carrier is a strip;
forming a filling encapsulant on the adhesive tape to fully fill
the stacked gaps between the stacked chips; fixing the tape carrier
on a wafer testing carrier to allow the substrate-less chip cubes
being loaded into a wafer tester without releasing from the
adhesive tape; wherein the wafer testing carrier has a disc-shaped
major body made of a hard material to provide a placing surface
larger than the adhesive tape, and the adhesive tape is completely
attached onto the placing surface so that the substrate-less chip
cubes are supported on the wafer testing carrier; and probing the
testing electrodes of the substrate-less chip cubes by a plurality
of testing probes inside a wafer tester to electrically test the
substrate-less chip cubes.
2. The method as claimed in claim 1, further comprising a step of
releasing the tape carrier from the wafer testing carrier after the
probing step.
3. The method as claimed in claim 1, wherein the wafer testing
carrier is larger than the tape carrier where both have different
shapes.
4. The method as claimed in claim 1, wherein the wafer testing
carrier has a plurality of fixing kits disposed on the major body
to fix the tape carrier.
5. The method as claimed in claim 4, wherein the fixing kits fix a
plurality of corners of the tape carrier when the tape carrier is
fixed.
6. The method as claimed in claim 1, wafer testing carrier further
has a fitting window sunk from the placing surface, wherein the
shape of the fitting window matches to the shape of the tape
carrier.
7. The method as claimed in claim 1, wherein the step of forming
the filling encapsulant includes a de-bleeding step of removing a
bleeding portion of the filling encapsulant exceeding the
footprints of the substrate-less chip cubes.
8. The method as claimed in claim 7, wherein the filling
encapsulant encapsulates a plurality of sidewalls of the chips
after the de-bleeding step.
9. The method as claimed in claim 1, wherein each chip has a
plurality of through silicon vias disposed inside, wherein a
plurality of interconnecting electrodes are disposed in the stacked
gaps between the stacked chips of the substrate-less chip cubes to
electrically connect the through silicon vias.
Description
FIELD OF THE INVENTION
The present invention relates to a manufacture method of
semiconductor devices, and more specifically to a method for
testing multi-chip stacked packages.
BACKGROUND OF THE INVENTION
Multi-chip packaging is an advanced high-density packaging
technology to vertically stacking a plurality of dice within the
same package. The existing packaging method is to stack individual
chips onto a substrate followed by corresponding packaging and
testing processes. However, using a substrate increases overall
package thickness and footprint.
In order to reduce the dimension of a multi-chip package, there is
an attempt to stack a plurality of chips using wafer-to-wafer
bonding to manufacture a substrate-less chip cube such as related
technology revealed in US Patent No. 2011/0074017. However, bad
chips are always randomly present within a wafer, therefore,
wafer-to-wafer bonding would cause overall packaging yield of
substrate-less chip cubes to drop. Moreover, when a substrate is
eliminated, the pitch between the external electrical electrodes
or/and the testing electrodes of a chip cube is shrunk from a few
hundred micrometer down below a hundred micrometer so that the
existing pogo pins of a tester for conventional semiconductor
packages can not be used. There are two solutions to resolve the
shrunk pitch issue. The first one is to directly SMT bond the
substrate-less chip cube onto a board without any testing followed
by a module test without ensuring the electrical joints between the
stacked chips good or bad. The other one is to directly mount the
substrate-less chip cube onto an interposer (normally made of Si)
with fan-out circuitry and fan-out electrodes then load the
interposer into a tester having pogo pins to perform testing where
the overall testing cost is quite complicated and expensive.
SUMMARY OF THE INVENTION
The main purpose of the present invention is to provide a method
for testing multi-chip stacked packages to achieve fine-pitch
probing of substrate-less chip cubes which can easily be integrated
into TSV packaging processes.
The second purpose of the present invention is to provide a method
for testing multi-chip stacked packages to test one or more
substrate-less chip cubes before SMT on boards and to reduce the
number of adhering steps of adhesive tapes to achieve lower
packaging cost and to prevent SMT bonding bad substrate-less chip
cube on boards.
According to the present invention, a method for testing multi-chip
stacked packages is revealed. Firstly, one or more substrate-less
chip cubes are provided, each of which consisting of a plurality of
vertically stacked chips where a stacked gap is formed between two
adjacent chips and each substrate-less chip cube has a plurality of
testing electrodes disposed on a top chip surface. Then, the
substrate-less chip cubes are attached onto an adhesive tape where
the testing electrodes are away from the adhesive tape with the
adhesive tape attached inside an opening of a tape carrier. Then, a
filling encapsulant is disposed on the adhesive tape to fully fill
the stacked gaps between adjacent chips. Then, the tape carrier is
fixed on a wafer testing carrier so that the substrate-less chip
cubes can be loaded into a wafer tester without releasing from the
adhesive tape. Finally, a plurality of testing probes of a probe
card mounted on the probe head of a wafer tester probe on the
testing electrodes to electrically test the substrate-less chip
cubes.
DESCRIPTION OF THE DRAWINGS
FIGS. 1A to 1I are cross-sectional component views illustrating
main processing steps of the method for testing multi-chip stacked
packages according to the preferred embodiment of the present
invention.
FIGS. 2A and 2B are a top view and a cross-sectional view of a
wafer testing carrier utilized in the method for testing multi-chip
stacked packages according to the preferred embodiment of the
present invention.
FIGS. 3A and 3B are a top view and a cross-sectional view of
another wafer testing carrier utilized in the method according to a
variant embodiment of the preferred embodiment of the present
invention.
FIG. 4 is a top view illustrating a tape carrier loaded on the
wafer testing carrier of FIG. 2A according to the preferred
embodiment of the present invention.
FIG. 5 is a three-dimensional view of a wafer tester implemented in
the method for testing multi-chip stacked packages according to the
preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
With reference to the attached drawings, the present invention is
described by means of the embodiment(s) below where the attached
drawings are simplified for illustration purposes only to
illustrate the structures or methods of the present invention by
describing the relationships between the components and assembly in
the present invention. Therefore, the components shown in the
figures are not expressed with the actual numbers, actual shapes,
actual dimensions, nor with the actual ratio. Some of the
dimensions or dimension ratios have been enlarged or simplified to
provide a better illustration. The actual numbers, actual shapes,
or actual dimension ratios can be selectively designed and disposed
and the detail component layouts may be more complicated.
According to the preferred embodiment of the present invention, the
method for testing multi-chip stacked packages is revealed where
cross-sectional component views of each processing step of the
method for testing multi-chip stacked packages is illustrated in
FIG. 1A to FIG. 1I.
FIG. 1A and FIG. 1B illustrate the manufacture processing flow of
the substrate-less chip cubes 100. Firstly, as shown in FIG. 1A, a
plurality of chips 110 are formed from dicing a wafer where a
plurality of testing electrodes 130 and a plurality of external
electrodes 131 are disposed on a top chip surface of each chip 110.
During dicing and after dicing, the chips 110 are adhered on a
dicing tape 210 where the dicing tape 210 is adhered to a wafer
frame (not shown in the figures). During dicing processes, a dicing
blade 220 cuts through the scribe lines of a wafer to form
individual chips 110. After wafer testing, known good dices 110 are
sorted and collected. As shown in FIG. 1B, a plurality of chips 110
are vertically stacked on a chip carrier 230 to form one or more
substrate-less chip cubes 100 where a stacked gap 120 is formed
between two adjacent chips 110 and a plurality of testing
electrodes 130 are disposed a top chip surface of each
substrate-less chip cube 100 where the testing electrodes 130 may
be metal pads or bumps. In this embodiment, the testing electrodes
130 are central pads exposed from the topmost active surface of the
top chip 110. Moreover, a plurality of external electrodes 131 are
disposed on the top chip surface of the topmost chip 110 such as
copper pillars, solder balls, or metal bumps where normally the
pitch between the testing electrodes 130 is larger than the pitch
between the external electrodes 131, the testing electrodes 130 are
electrically connected with the corresponding external electrodes
131. In the present embodiment, the pitch between the testing
electrodes ranges from 60 um to 100 um and the pitch between
external electrodes 131 ranges from 30 um to 60 um. In a various
embodiment, the external electrodes 131 can be eliminated and the
testing electrodes 130 can be used also as the external electrodes
131. As shown in FIG. 1B, in the present embodiment, each chip 110
has a plurality of TSVs (through silicon vias) 111 inside which are
electrically connected to the external electrodes 131 where the
TSVs 111 and the external electrodes 131 may be vertically
connected and RDL (not shown in the figures) is implemented to
electrically connect to the testing electrodes 130. Furthermore, a
plurality of interconnecting electrodes 140 are disposed between
the stacked gaps 120 of the substrate-less chip cubes 100 to
electrically connect the TSVs 111. The interconnecting electrodes
140 can be formed by the external electrodes 131 of the chips 110
before chip stacking or by additionally disposed components such as
the combination of metal pillars and solder paste.
Then, as shown in FIG. 1C, the substrate-less chip cubes 100 are
attached onto an adhesive tape 252 where the testing electrodes 130
are away from the adhesive tape 252. The adhesive tape 252 has
adhesive to adhere the substrate-less chip cubes 100. The adhesive
tape 252 is also attached inside an opening 251 of a tape carrier
250 as shown in FIG. 1F where normally the tape carrier 250 is
strip-like metal frame. The step of disposing the adhesive tape 252
on the tape carrier 250 can be performed before or after the step
of forming a filling encapsulant. In the present embodiment, the
step of disposing the adhesive tape 252 disposed on the tape
carrier 250 is performed after dispensing and before curing the
filling encapsulant where the tape carrier 250 is implemented as a
loading carrier to transfer the substrate-less chip cubes 100 into
a baking oven.
Then, as shown in FIG. 1C again, a filling encapsulant 150 is
provided by a dispensing needle 240 where the filling encapsulant
150 is formed on top of the adhesive tape 252 and the filling
encapsulant 150 is able to completely fill the stacked gaps 120
under appropriate temperatures with appropriate time to create
capillary attraction and encapsulate the interconnecting electrodes
140 as shown in FIG. 1D. Then, the filling encapsulant 150 is
thermally cured by a baking oven.
As shown from FIG. 1D to FIG. 1E, in the aforementioned described
step of forming the filling encapsulant 150 includes a de-bleeding
step of removing a bleeding portion 151 of the filling encapsulant
150 exceeding the footprints of the substrate-less chip cubes 100
to make the substrate-less chip cubes 100 more like a cube. The
aforementioned described step of removing bleeding can be performed
before or after curing the filling encapsulant 150. For example,
when the de-bleeding step is performed after curing the filling
encapsulant 150, the bleeding 151 can be removed by a laser cutting
tool. In the present embodiment, the aforementioned described
de-bleeding step can be performed before curing the filling
encapsulant 150 by exposure and development. As shown in FIG. 1E,
preferably, after the de-bleeding step, the filling encapsulant 150
still encapsulates a plurality of sidewalls 112 of the chips 110 to
effectively protect the chips 110 stacked in the substrate-less
chip cubes 100.
Then, as shown in FIG. 1G, the tape carrier 250 is fixed on a wafer
testing carrier 260 to allow the substrate-less chip cubes 100
without releasing from the adhesive tape 252 to be loaded into a
wafer tester 270 as shown in FIG. 1H. As shown in FIG. 4, the wafer
testing carrier 260 can be larger than the tape carrier 250 where
both can have different shapes where the wafer testing carrier 260
can carry the tape carrier 250 to form interchangeable modularized
jigs. In the present embodiment, the wafer testing carrier 260 is a
round disc having a ring looked like a conventional wafer frame.
However, in the present embodiment, the major difference between
the wafer testing carrier 260 and the conventional wafer frame is
that there is no opening penetrating through the wafer testing
carrier 260 and there is no dicing tape to adhere a wafer through
the wafer testing carrier 260. The shape of the tape carrier 250
can be strip-like such as substrate strips for transferring
substrates.
As shown in FIG. 2A and FIG. 2B, in the present embodiment, the
wafer testing carrier 260 may have a disc-like major body 261 made
of hard materials such as copper, iron, or alloy to provide a hard
placing surface 263 for carrying the tape carrier 250. To be more
specific, the wafer testing carrier 260 has a plurality of fixing
kits 262 disposed on the placing surface 263 of the major body 261
to position the tape carrier 250. As shown in FIG. 4, the clamps
262 can clamp a plurality of corners 253 of the tape carrier 250
where the tape carrier 250 has an adhesive tape 252 adhered the
substrate-less chip cubes 100. Therefore, the substrate-less chip
cubes 100 accompanied with the tape carrier 250 can be loaded into
a wafer tester 270 though the wafer testing carrier 260 without
releasing from the adhesive tape 252.
As shown in FIG. 3A and FIG. 3B, in a various embodiment, the major
body 261 of the wafer testing carrier 260 further has a fitting
window 264 sunk from the placing surface 263 with a shape matching
to the shape of a tape carrier 250. When the tape carrier 250 is
installed on the placing surface 263, the bottom portion of the
tape carrier 250 is partially embedded into the fitting window 264
to achieve fixing the tape carrier 250 on the wafer testing carrier
260.
Then, as shown in FIG. 1H, the wafer testing carrier 260 is loaded
inside the wafer tester 270, and a plurality of testing probes 271
inside the wafer tester 270 can probe on the testing electrodes 130
to electrically test the substrate-less chip cubes 100 where the
testing probes 271 are installed on a probe card 275. As shown in
FIG. 5, the wafer tester 270 includes a loading zone 272, a loading
lock 273, and a testing zone 274 where wafer frames can be loaded
and unloaded in the loading zone 272 and then transferred to the
testing zone 274 after alignment check in the loading lock 273. The
afore probe card 275 including the testing probes 271 is disposed
in the testing zone 274 for electrical testing the testing
electrodes 130 disposed on wafer surfaces. Since the wafer testing
carrier 260 can meet the dimension of wafer frames and can directly
be loaded into the loading lock 273 so that the testing probes 271
inside the testing zone 274 can probe the testing electrodes 130 of
the substrate-less chip cubes 100 without releasing from the
adhesive tape 252, without another transferring the substrate-less
chip cubes 100 to another adhesive tape 252 and without changing
the tape carrier 250 to reduce the testing cost, to increase the
testing efficiency of wafer-level testing of multi-chip packages,
and to meet the requirement of fine-pitch probing so that the
substrate-less chip cubes 100 can be tested without disposed on an
interposer with fan-out circuitry and fan-out electrodes to confirm
the electrical connection between the stacked chips 110, i.e., the
electrical connection between interconnecting electrodes 140.
Furthermore, the method for testing multi-chip stacked packages of
the present invention allows directly sorting the substrate-less
chip cubes 100 inside the wafer tester 270 to sort out or remove
bad substrate-less chip cube 100.
As shown in FIG. 1I, after testing, the method for testing
multi-chip stacked packages further comprises the step of releasing
the tape carrier 250 from the wafer testing carrier 260 so that the
wafer testing carrier 260 can be recycled. Moreover, the following
steps may comprise marking, packing, and so on.
Therefore, the method for testing multi-chip stacked packages of
the present invention can be implemented in the existing wafer
tester to achieve probing of fine-pitch electrodes of the
substrate-less chip cubes 100 without an interposer to provide good
substrate-less chip cubes 100 and to sort out good and bad
substrate-less chip cubes 100 to reduce the number of adhering
processes of the adhesive tape to achieve lower packaging cost and
to prevent SMT bad substrate-less chip cube on boards.
The above description of embodiments of this invention is intended
to be illustrative but not limited. Other embodiments of this
invention will be obvious to those skilled in the art in view of
the above disclosure which still will be covered by and within the
scope of the present invention even with any modifications,
equivalent variations, and adaptations.
* * * * *